Вопрос по выравниванию высоты блоков с помощью flexbox

body {
  margin: 0;
}
.list {
  display: flex;
  flex-direction: row;
  overflow-x: auto;
}
.list__item {
  display: flex;
  flex-direction: column;
  border: .2em solid blue;
  margin-left: 1em;
  flex-basis: 30%;
}
.list__item__block {
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: .5em;
  box-sizing: border-box;
  width: 100%;
  margin-top: .5em;
  border-bottom: .1em solid blue;
}
.list__item__block:nth-child(3) {
  flex-grow: 1;
}

<div class='list'>
  <div class='list__item'>
    <div class='list__item__block'>Block 1</div>
    <div class='list__item__block'>Block 2</div>
    <div class='list__item__block'>Very very very very very very very very very very very very very very very very very very very very very very very very very very very very very big block 3</div>
    <div class='list__item__block'>Block 4</div>
  </div>
  <div class='list__item'>
    <div class='list__item__block'>Block 1</div>
    <div class='list__item__block'>Block 2</div>
    <div class='list__item__block'>Block 3</div>
    <div class='list__item__block'>Block 4</div>
  </div>
  <div class='list__item'>
    <div class='list__item__block'>Block 1</div>
    <div class='list__item__block'>Block 2</div>
    <div class='list__item__block'>Block 3</div>
    <div class='list__item__block'>Block 4</div>
  </div>
</div>